Copper alloy foil

Abstract

For a two-layer printed wiring board including a polyimide substrate produced with varnish containing polyamic acid as the raw material for the polyimide and a copper alloy foil laminated with the polyimide substrate, there is provided, for the copper alloy foil, a copper alloy containing, in addition to copper and unavoidable impurities, either (1) 0.02 to 1.0 weight percent Ag and/or 0.01 to 0.5 weight percent In or (2) alloy composition (1) plus a total of 0.005 to 2.5 weight percent of at least one of the additional elements Al, Be, Co, Fe, Mg, Mn, Ni, P, Pb, Si, Ti and Zn, or (3) 0.001 to 0.5 weight percent Sn or (4) alloy composition (3) plus a total of 0.005 to 2.5 weight percent of at least one of the additional elements of alloy composition (2) and each of (1), (2), (3) and (4) preferably having a heat resistance of at least 300° C.

What is claimed is:  
     
       1. A laminate comprising a copper alloy foil laminated with a polyimide substrate formed by thermosetting polyamic acid contained in a varnish, the copper alloy foil having a surface exhibiting no roughening plating processing and the copper alloy foil consisting of at least one of 0.02 to 1.0 weight percent Ag and 0.01 to 0.5 weight percent In, the balance Cu and unavoidable impurities, said surface of the copper alloy foil being coated with an anticorrosive coating of thickness less than 5 nm and comprising benzotriazole or imidazole and onto which coating the varnish containing polyamic acid is applied before said thermosetting, the anticorrosive coating exhibiting good wettability with the varnish containing polyamic acid, and the copper alloy foil exhibiting conductivity of at least 80% IACS and 180° peel strength between the copper alloy foil coated with the anticorrosive coating and the polyimide substrate of at least 8.0 N/cm. 
     
     
       2. A laminate comprising a copper alloy foil laminated with a polyimide substrate formed by thermosetting polyamic acid contained in a varnish, the copper alloy foil having a surface exhibiting no roughening plating processing and the copper alloy foil consisting of at least one of 0.02 to 1.0 weight percent Ag and 0.01 to 0.5 weight percent In, a total of 0.005 to 2.5 weight percent of at least one of Al, Be, Co, Fe, Mg, Mn, Ni, P, Pb, Si, Ti and Zn, the balance Cu and unavoidable impurities, said surface of the copper alloy foil being coated with an anticorrosive coating of thickness less than 5 nm and comprising benzotriazole or imidazole and onto which coating the varnish containing polyamic acid is applied before said thermosetting, the anticorrosive coating exhibiting good wettability of the anticorrosive coating with the varnish containing polyamic acid, and the copper alloy foil exhibiting tensile strength of at least 500 N/mm 2 , conductivity of at least 60% IACS and 180° peel strength between the copper alloy foil coated with the anticorrosive coating and the polyimide substrate of at least 8.0 N/cm. 
     
     
       3. A laminate comprising a copper alloy foil laminated with a polyimide substrate formed by thermosetting polyamic acid contained in a varnish, the copper alloy foil having a surface exhibiting no roughening plating processing and the copper alloy foil consisting of 0.01 to 0.5 weight percent Sn, the balance Cu and unavoidable impurities, said surface of the copper alloy foil being coated with an anticorrosive coating of thickness less than 5 nm and comprising benzotriazole or imidazole and onto which coating the varnish containing polyamic acid is applied before said thermosetting, the anticorrosive coating exhibiting good wettability with the varnish containing polyamic acid, and the copper alloy foil exhibiting conductivity of at least 70% IACS and 180° peel strength between the copper alloy foil coated with the anticorrosive coating and the polyimide substrate of at least 8.0 N/cm. 
     
     
       4. A laminate comprising a copper alloy foil laminated with a polyimide substrate formed by thermosetting polyamic acid contained in a varnish, the copper alloy foil having a surface exhibiting no roughening plating processing and the copper alloy foil consisting of 0.01 to 0.5 weight percent Sn, a total of 0.005 to 2.5 weight percent of at least one of Al, Be, Co, Fe, Mg, Mn, Ni, P, Pb, Si, Ti and Zn, the balance Cu and unavoidable impurities, said surface of the copper alloy foil being coated with an anticorrosive coating of thickness less than 5 nm and comprising benzotriazole or imidazole and onto which coating the varnish containing polyamic acid is applied, the anticorrosive coating exhibiting good wettability with the varnish containing polyamic acid, and the copper alloy foil exhibiting tensile strength of at least 500 N/mm 2 , conductivity of at least 60% IACS and 180° peel strength between the copper alloy foil coated with the anticorrosive coating and the polyimide substrate of at least 8.0 N/cm. 
     
     
       5. A laminate according to any one of claims  1 - 4 , wherein the heat resistance of the copper alloy foil is at least 300° C., the heat resistance of the copper alloy foil being a temperature at which the tensile strength of the copper alloy foil after heating thereof for one hour is intermediate between the tensile strength of the copper alloy foil before said heating thereof and the tensile strength which the copper alloy foil would exhibit after softening thereof.